I'm studying an application for a version of the classic Hoffman Apparatus .Can you all help me dig up answers to questions on Hoffman Apparatus and/or pass these questions on to those who might be able to contribute some info?

1) Primarily what are the factors or conditions needed to increase gas production (whether it be larger vessels with larger/ more cathode/anodes, more amps, optimum choice of electrolytes)?I want to eliminate as options exotic or expensive materials (i.e. platinum, or extreme electrolytes, etc),

2) Is there a correlation or optimum ratio of surface area of electrodes (anode/cathode) to electrical current supply?

3) Do the anodes and cathodes have differing material requirements from each other, i.e. should the anode be graphite, but the cathode be stainless steel, or some other differing set of materials?

4) Relevance? Geometry and mass of the electrodes (see attached hypothetical stainless steel configuration and a graphite rod)? .... and also ratio of electrode volume/geometry to the electrolyte solution volume (i.e. differences if the positive and negative vessels are sized to minimize electrolyte volumes around electrodes ... small electrolyte to electrode mass ratio)?